1 8 



Scientific Proceedings (25). 



graftings in this group of animals as compared with the low per- 

 centage in those spontaneously recovering without the emulsion, 

 namely 30 as compared with 9 per cent. If, however, this group 

 be compared with the group in which after spontaneous recovery 

 heated emulsion was injected for the first time and followed by new 

 grafts, the percentage of successful re-inoculations is identical in 

 both, namely 30 per cent. 



It would be premature to attempt a discussion of this interest- 

 ing and unexpected fact, since it seems to imply that by the injec- 

 tion of the heated emulsion a state of susceptibility to tumor im- 

 plantations can be preserved while, at the same time, the originally 

 implanted tumor has suffered spontaneous absorption. 



The next experiment was devised to determine the effects to 

 be obtained from rat serum. Four sera were employed : (a) From 

 normal rats ; (b) from rats which did not develop tumors after 

 repeated inoculations (normally immune) ; {c) from rats in which 

 the tumors disappeared spontaneously (artificially immune) ; and 

 (d) from rats with growing tumors. Bouillon and horse serum 

 were used as controls. All specific effects were absent, that is, the 

 sera neither inhibited nor promoted the growth of the grafts, while 

 the bouillon seemed to be somewhat, and the horse serum rather 

 more, inhibitory. 



Finally, heated and unheated emulsions of various organs, 

 liver, spleen, kidney, muscle and testicle were tested. No pro- 

 motion or inhibition of growth was noted. With this experiment 

 was combined still another test with the heated and unheated tumor 

 emulsion. All the animals, controls included, received grafts of 

 the same tumor on the same day, that is, ten days after injection 

 of the emulsions. The control rats and the rats injected with 

 organic emulsions gave 80 per cent, of successful implantations. 

 The rats which received unheated tumor emulsion showed 60 per 

 cent, and those which received heated tumor emulsion showed 100 

 per cent, of growths. 



